1. Field of the Invention
The present invention relates to a method for forming a thick film pattern by using photolithography, a method for manufacturing an electronic component, and a photolithography photosensitive paste to be used for forming a thick film pattern via photolithography.
2. Description of the Related Art
As densities have been increased and signal speeds have been increased for high-frequency electronic apparatuses, patterns, e.g., wiring conductors, constituting high-frequency circuits provided in these apparatuses have been required to be fine, have large film thicknesses, have rectangular cross-sectional shapes, and furthermore, have wiring precision with very narrow ranges of variations in wiring dimensions.
A method for forming a pattern via photolithography has been widely used as a method for forming such a fine pattern. For example, a photosensitive paste containing an inorganic powder, a photosensitive monomer, a polymer, a photopolymerization initiator, and the like has been proposed and known as the photosensitive paste to be used therein (for example, Japanese Unexamined Patent Application Publication No. 2002-82449).
However, in the case where patterns are formed via photolithography, known photosensitive pastes have a problem in that an adequate photo-curing depth (a depth from a thick film surface, at which the energy of radiated light, e.g., ultraviolet light, travelling in the thick film falls below the minimum energy required for curing a resin due to attenuation by being consumed for curing the resin or being absorbed by the resin component) cannot be ensured.
The inventors of the present invention found that the polymer exerted an influence on this photo-curing depth. The reasons for this are believed to be that (a) the radiated light is refracted and scattered by the polymer and, therefore, it becomes difficult for the ultraviolet light to reach the inside of the photosensitive paste, (b) the ultraviolet light is absorbed by the polymer, and (c) when the polymer is contained, the micro-Brownian motion of the monomer in the photosensitive paste is hindered and, thereby, the polymerization becomes hard to proceed.